The present invention is in the field of measurement techniques for measuring various properties/parameters of samples, and relates to a measurement method and system particularly useful for determining strain distribution in a sample, such as a semiconductor structure.
Various optical measurement techniques have been developed for measuring the strain and other properties of a material.
For example, U.S. Pat. No. 8,437,450 describes a method for analysis including directing a converging beam of X-rays toward a surface of a sample having multiple single-crystal layers, including at least a first layer and a second layer that is formed over and tilted relative to the first layer. The X-rays that are diffracted from each of the first and second layers are sensed simultaneously while resolving the sensed X-rays as a function of angle so as to generate a diffraction spectrum including at least a first diffraction peak due to the first layer and a second diffraction peak due to the second layer. The diffraction spectrum is analyzed so as to identify a characteristic of at least the second layer. This technique enables determination of average strain and relative material concentrations.
The ongoing progress of semiconductor technology leads to shrinking device dimensions as well as more complex device designs. Characterization of modern semiconductor devices presents an incredibly challenging task, requiring suitable metrology tools, which are critical for the continual process of this development.
Several metrology technologies have been developed for semiconductor device characterization. Examples are CD-SEM, utilizing the high resolution allowed by electron microscopy, and Optical Critical Dimension (OCD) metrology.